1. Field of the Invention
This invention relates to a curable fluorosilicone rubber composition, and, particularly, to a composition that can give a cured product having a silicone fluid-bleeding property.
2. Prior Art
Fluorosilicone rubber, which not only has good oil and solvent resistance but also has good thermal resistance and low temperature resistance, can be useful when used under the severe conditions when these properties are required.
In respect of silicone rubber compositions (or compounds) principally composed of a dimethyl polysiloxane compound, there has been hitherto put into practical use a technique of incorporating a non-compatible fluid silicone compound as a bleed component in an adequate amount to obtain a cured product whose surface can exhibit the fluid-bleeding property, and a silicone fluid containing 5 to 25% of phenyl group as organic groups has been used as the bleed component.
In respect also of the above-mentioned fluorosilicone rubber, it can be contemplated that the fluid-bleeding property can be imparted to a cured product according to the same procedures as in the case of the above silicone rubber prinicipally composed of dimethyl polysiloxane. However, even if a fluorosilicone rubber composition is prepared according to the same procedures as in the conventional silicone rubber compositions principally composed of dimethyl polysiloxane, the resulting cured product can exhibit no sufficient fluid-bleeding property when the silicone fluid to be used as the bleed component, whether it is dimethyl silicone fluid or phenylmethyl silicone fluid, is contained in an amount of 10% or less. When it is in amount of 12 to 15%, the bleeding property can be exhibited, but the processability of the composition obtained may be seriously impaired and also the oil and solvent resistance which is an advantageous feature inherent in fluorosilicone rubber may be seriously lowered, thus raising a problem that the product is not suited for practical use.